UHMW warping while fusing to glass filled HDPE

[ykamms]

Hello,
I am trying to fuse UHMW to glass filled HDPE tape and am having the UHMW warp and create large creases. My setup now is inside a vacuum bag I have a silicone heating blanket at 400F on top of the glass filled HDPE with the UHMW under that and lastly it sits on a steel sheet to help keep it flat.

I am thinking possibly I am ramping up the temperature too quickly or that I need a mechanical press to create more pressure..


Thank you

 

[patprimmer]

You have differential expansion going on due to temperature profile across the UHMWPE. Also the glass fibre reinforced HDPE will have a substantially different c-efficient of thermal expansion and also a different temperature change due to positioning of the heater.

I would heat evenly and slowly from both sides and cool evenly and slowly on both sides.

You might also need to apply the glass fibre to both sides if that is possible.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[Demon3]

To exemplify what Pat just said. Did you ever see a bimetallic strip at school? You heat it and because the two metals expand by differing amounts, the strip bends. That's what you've made but in polymer form.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[Compositepro]

You will have very poor temperature uniformity with a heat blanket. Fix this issue first and then you can work on any others.

 

[ykamms]

Thank you!